Magnetic door latch



M- HEKELAAR ETAL Aug. 8,,1 967 MAGNETIC DOOR LATCH Filed March a; 1965 3 2 Sheets-Sheet 1 Fl-G.4

I INVENTORJ MAARTEN HEKELAAR gI LH ELMUS H. VAN DONSELAAR AGENT Aug 8, 967 M. HEKELAAR IETAL MAGNETIC DOOR LATCH 2 Sheets-Sheet 2 Filed March 8, 1965 FIG.5

INVENTORJ MAARTEN HEKELAAR WIKLHELMUS a. VAN DONSELAAR AGEN T United States Patent Ofiice 3,334,936 Patented Aug. 8, 1967 3,334,936 MAGNETIC DOOR LATCH Maarten Hekelaar and Wilhelmus Hendrikus van Donselaar, Emmasingel, Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N .Y., a corporation of Delaware Filed Mar. 8, 1965, Ser. No. 437,782

Claims priority, application Netherlands, Apr. 8, 1964,

3 Claims. (Cl. 292251.5)

The invention relates to a door latch comprising a locking bolt co-operating with a soft-iron jamb plate and a handle secured to a tumbler which operates to tilt the bolt before separating the bolt and locking plate or vice versa.

The invention has for one object to provide a door latch, the size of which is such that thickness of the doors in which such locks are mounted may be much smaller than in the case of mechanical locks, while effective latching of the door is not adversely affected.

The invention is characterized in that in the closed state of the latch the bolt and the jamb plate are held together by magnetic force of attraction.

The invention has the following additional objects:

By employing magnetic materials the door locks are small and hence inexpensive.

Moreover, magnetic locks can be actuated so that wear is at a minimum.

When the bolt consists of a permanent magnet the advantage is obtained that no recess is required in the door post or jamb. In the case of mechanical locks the associated door post is practically always provided with a recess for accommodating the lock bolt, when the door is closed. Providing such a recess takes time and may, under certain conditions, bring about weakening of the door post.

It is generally known,'in disengaging a permanent magnet from a soft-iron strip to tilt the two parts relatively to each other, so that a small attractive force is left between the parts (linear contact), which can be overcome by a very small force. The essential parts, i.e. bolt and jamb plate, of the lock according to the invention are disengaged in this manner. That is, there are two distinct movements for accomplishing separation, first a tilting of the bolt with respect to the jamb and second a retraction of the bolt from the jamb.

In the embodiments of the invention to be described, the bolt may be held fully withdrawn When the door is opened. With mechanical locks the lock bolt practically always projects, so that clothing may readily hook on it.

With reference to the drawing a presently preferred embodiment of the invention will now be described more fully.

FIG. 1 is a longitudinal sectional view of a latch according to this invention.

FIG. 2 is a cross sectional view of the latch taken on the line IIII in FIG. 1.

FIG. 3 shows the tumbler of said latch on an enlarged scale.

FIG. 4 is a plan view of said tumbler and FIG. 5 shows another embodiment of the magnetic latch according to the invention.

The magnetic latch comprises a brass housing I having a recess 2 for accommodating a bolt generally designated 3. Said bolt is to some extent freely movable in the recess and may project slightly from the housing 1 on the front side beyond the sheathing 4. The bolt 3 consists of a fiat magnet 5 of Magnadur, which is magnetised in the direction of thickness, and which is provided on two opposite sides with pole pieces 6 and 7. The housing 1 is fastened to a door 8 in a conventional manner,

by screws 9, and is provided with a tumbler 10, which is fastened to a shaft 11. The shaft projects from the door 8 on either side and may beprovided with a known knob or handle conventionally used with mechanical latch assemblies.

The tumbler 10 co-operates with the magnetic bolt 3 by virtue of the pole pieces 6 and 7 of the bolt which are prolonged to the rear and are connected by a pin 12. Said pin is coupled with a lug 13 of the tumbler 10 in a conventional manner, and acts as a cam follower when the tumbler is rotated, along a camming or profiled surface of recess 14 which has an ascending portion 15. The free end of bolt 3 co-operates with a ferro-magnetic jamb plate 16, also termed an armature, which is provided with a shallow cavity 17 and which is secured to the door post 18 in a conventional manner by wood screws. When the door is closed the front side of the bolt 3 is located in the cavity 17 of the armature 16. When the 'door is opened, the door knob or handle (not shown) is turnedso that the tumbler 10 also turns and the lug 13 moves to the left. The profiled surfaces of recess 14 come into contact with the pin 12; which first slides along the ascending portion 15. The pin 12 moves upwardly and as a result the bolt 3 tilts relative to armature 16 around the edge 19 of the bolt. When the knob is turned further, the pin 12 slides further on the surface 14 and abuts against the bottom wall of the recess in the lug 13 which'provides the force required to separate the bolt 3 from the armature 16. The door knob, and consequently the shaft 11, is returned to its initial position when the door is open and the knob released by means of a tensile spring 20 connected at one end with lug 13 and at its other end with the rear side of the sheathing 4. In order to prevent the bolt from projecting beyond the sheathing 4 to an excessive extent, the bolt is furthermore provided with a stop 21 which co-operates with the set screw 22, provided in the sheathing, and adjusted from the outside in a simple manner. The tumbler 10 is provided with a stop 23 for preventing the handle from being turned further than necessary to withdraw the bolt. Tumbler stop 23 co-operates with the lower side 24 of the housing. In order to close the door conveniently, the armature 16 is provided with a wedgeshaped face 25, along which the pole piece 7 having a round edge 26 glides.

FIG. 5 shows another embodiment of a magnetic latch according to the invention, in which a recess 31 is pro- .vided in a door 30; there is shown diagrammatically a structure which comprises a ferromagnetic, lever-like locking plate 32 of soft-iron material. A shaft 33 is provided in said door and may be provided on either side, in a conventional manner, with a handle (not shown). The shaft 33 is furthermore provided with a tumbler 34 which co-operates with the lever 32. The figure shows furthermore a door post 35 in which a brass housing 36 is provided which has a recess 37 for accommodating a magnetic bolt 38 with a certain amount of clearance. This bolt consists of a flat Magnadur magnet having pole pieces, said magnet co-operating at the front end with the lever 32.

When the latch is opened, the shaft 23 is turned in the direction of the arrow. The tumbler 34 then pushes the lever 32 in downward direction. The bolt 38 is urged into the door post, while at the same time the armature 32 tilts about the fulcrum 39. The fulcrum also has a second lever 40, which bears on fiat part 41 of the tumbler 34 in the closed state of the latch, and lever 40 is furthermore connected by a tensile spring 42 with the armature or lever 32. In the opened state of the latch the leverlike armature 32 as well as the door knob, are returned to their initial position by the spring 42. In order to prevent the bolt 38 from coming out of the housing 36, when the door is open, the housing 36 is provided on the rear side with a soft-iron strip 43, which extends across the top side and the lateral sides of the recess 37 in the housing 36. Said strip 43 exerts a small force on the magnetic bolt 38, which is thus drawn to the left in the figure. The magnetic latch of this structure is particularly suitable for use in very thin doors and, moreover, in those cases, where between the door and the door post little clearance is available.

What is claimed is:

1. A magnetic door latch assembly comprising a magnetic bolt, housing means supporting said bolt, armature means for attracting said bolt for latching said door, and tumbler means coupled with a rotatable door shaft for releasing said bolt and interconnecting said magnetic bolt and said armature, the connection between the tumbler means and the magnetic bolt comprising cam means integral with said tumbler, and cam follower means integral with said magnetic bolt and in cooperative relation with said cam means whereby rotation of said door shaft will cause said cam follower to move relative to said cam thereby first tilting said bolt and then retracting said bolt from engagement with said follower.

2. A magnetic door latch according to claim 1 wherein said tumbler means further comprises a tumbler having a lug portion on one end of said tumbler, said lug portion having a profiled camming recess; said bolt having a cam following yoke coupled with said lug portion, said yoke having a pin operatively receivable in said profiled recess, said profiled recess being configured to tilt said bolt upon the initial movement of said door knob shaft and upon continued movement of said door knob shaft retracting said bolt for separating said bolt from said armature.

3. A magnetic door latch according to claim 2 wherein said armature comprises a jamb plate having a ramp portion and a recess for receiving said bolt.

References Cited UNITED STATES PATENTS 2,194,601 3/ 1940 Kuethe 292-254 2,786,702 3/ 1957 Teetor 292-2515 2,808,281 10/1957 Poe 292-251.5 2,970,857 2/ 1961 Squire 292-2515 FOREIGN PATENTS 1,341,221 9/1963 France.

145,325 11/1903 Germany.

MARVIN A. CHAMPION, Primary Examiner.

RICHARD E. MOORE, Examiner. 

1. A MAGNETIC DOOR LATCH ASSEMBLY COMPRISING A MAGNETIC BOLT, HOUSING MEANS SUPPORTING SAID BOLT, ARMATURE MEANS FOR ATTRACTING SAID BOLT FOR LATCHING SAID DOOR, AND TUMBLER MEANS COUPLED WITH A ROTATABLE DOOR SHAFT FOR RELEASING SAID BOLT AND INTERCONNECTING SAID MAGNETIC BOLT AND SAID ARMATURE, THE CONNECTION BETWEEN THE TUMBLER MEANS AND THE MAGNETIC BOLT COMPRISING CAM MEANS INTEGRAL WITH SAID TUMBLER, AND CAM FOLLOWER MEANS INTEGRAL WITH SAID MAGNETIC BOLT AND IN COOPERATIVE RELATION WITH SAID CAM MEANS WHEREBY ROTATION OF SAID DOOR SHAFT WILL CAUSE SAID CAM FOLLOWER TO MOVE RELATIVE TO SAID CAM THEREBY FIRST TILTING SAID BOLT AND THEN RETRACTING SAID BOLT FROM ENGAGEMENT WITH SAID FOLLOWER. 